Regeneron to Discontinue Development of Suptavumab for RSV

Antibody failed to meet primary endpoint in phase 3 trial

Disappointing results of a phase 3 trial evaluating suptavumab for respiratory syncytial virus (RSV) have led Regeneron Pharmaceuticals to discontinue further clinical development. In the study, suptavumab (REGN2222), an antibody to RSV, did not meet its primary endpoint of preventing medically-attended RSV infections in infants.

"We are disappointed in these results, as we had hoped suptavumab might offer a new option for the thousands of infants impacted by serious RSV infections every year," said George D. Yancopoulos, MD, PhD, President and Chief Scientific Officer of Regeneron.

The double-blind, placebo-controlled global phase 3 NURSERY Preterm study enrolled 1,149 healthy preterm infants. Patients were randomized in a 1:1:1 ratio to one of three study groups: suptavumab 30 mg/kg as a single dose; suptavumab 30 mg/kg administered as two doses eight weeks apart; or placebo. Assessment of the primary endpoint occurred through day 150 of treatment.  Patients were considered “medically-attended” if they required hospitalization and/or sought medical care for a centrally adjudicated RSV infection. Preterm infants in the study had a gestational age of less than 36 weeks and were 6 months old or younger at the beginning of the study.

Suptavumab did show signs of efficacy in a subgroup of patients. Adverse events were generally balanced between suptavumab and placebo.  Data from the study will be presented at a future medical congress.

Source: Regeneron Pharmaceuticals, Inc.; August 14, 2017.